Sealing caps

ABSTRACT

A one-piece plastics diaphragm for a petrol cap, and which replaces the conventional assembly of spring, backing plate, and sealing ring, the diaphragm having at its edge an annular wall which is spaced from the body of the cap, and a further wall which has an axial extent, the further wall being deformed by the pressure between the annular wall and the filler neck during manual application so that the two walls of the diaphragm seal tightly against the inner surface and the rim of the neck, the sealing engagement being maintained merely by the fastening engagement between the cap body and the filler neck.

United States Patent 1191 Fernberg et al.

[ 5] Nov. 25, 1975 1 SEALING CAPS [75] Inventors: Paul C. Fernberg, Farnham Common; Colin W. F. Clinch, Woodley, both of England [52] US. Cl. 220/295; 220/308; 220/302;

220/373; 220/378 [51] Int. Cl. B65D 53/00; B65D 51/16 [58] Field of Search 220/24 GT, 60 R, 46 R,

220/44 R, 44 A, 44 C, 295, 302, 308, 323, 378, 303, 367, 373, 374; 215/317, 343

3,516,569 6/1970 Goes 2.20/46 R FOREIGN PATENTS OR APPLICATIONS 753,609 7/1956 United Kingdom 220/373 Primary E.\'aminerWilliam Price Assistant E.raminer-Joseph M. Moy

Attorney, Agent, or Firm.l. R. l-lalvorsen; R. W. Beart [57] ABSTRACT A one-piece plastics diaphragm for a petrol cap, and which replaces the conventional assembly of spring, backing plate, and sealing ring, the diaphragm having at its edge an annular wall which is spaced from the body of the cap, and a further wall which has an axial extent, the further wall being deformed by the pressure between the annular wall and the filler neck during manual application so that the two walls of the diaphragm seal tightly against the inner surface and the rim of the neck, the sealing engagement being maintained merely by the fastening engagement between the cap body and the filler neck.

1 Claim, 3 Drawing Figures US. Patent Nov. 25, 1975 SheetlofZ 3,921,849

U.S. Patent Nov. 25, 1975 Sheet2of2 3,921,849

SEALING CAPS This invention Concerns petrol cap assemblies.

Cap assemblies are applied to filler necks ofpetrol tanks on automobiles. They are applied by manual, axially inward pressure against a spring action; then a small clockwise turn causes a fastening engagement to occur between means provided on the cap, and cooperating means on or in the vicinity of the neck. At the end of the small turn it is arranged for the spring to urge the cap to its fastened condition and maintain a seal in the cap to operate against the rim of the filler neck.

It is necessary for the cap to be removable from the neck by a short anticlockwise turn which means, in effect, that the seal cannot hold itself on the neck by frictionally gripping the outer or inner surfaces of the neck, but must rely on simply abutting the circular or annular rim i.e., the edge or edge face of the neck.

One automobile firm specify that the seal, to be safe, must withstand a head of 300 cms of petrol, which can happen when the automobile is inverted in an accident. In the cap assemblies in which a vent is provided through the cap, they specify further that the loss rate of petrol through the vent must be less than 6 ccs in minutes, and not more than 5 ccs in any one minute.

Known caps have achieved the seal by an annular corrugated spring positioned between the body of the cap and a backing plate which is held in the cap. A flexible sealing ring is mounted on the other side of the backing plate. The cap assembly therefore has to carry a central turret about which is mounted a spring, a backing plate and a sealing ring. These components have to be manufactured separately and assembled.

The present invention is particularly concerned with replacing the assembly of the spring, sealing ring and backing plate in conventional caps.

According to this invention a petrol cap assembly comprises a cap body and a one-piece plastics diaphragm, the diaphragm being substantially continuous and comprising a first wall which extends a substantial distance in the direction of the axis of the body, and a second annular wall which extends radially outwards at the edge of the diaphragm and in the relaxed condition lies spaced axially from the cap body; the arrangement being such that when the cap is progressively pressed onto the filler neck of a petrol tank the second wall abuts with increasing pressure the rim of the neck, and causes the diaphragm to deform in such a manner as to force the first wall to form a continuous seal against the interior of the neck, that seal between the two walls of the diaphragm and the two surfaces of the neck, being maintained only by a fastening means operative between the cap head and the tiller neck.

One cap assembly having a diaphragm constructed in accordance with this invention is particularly described below with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation of the assembly, the lower half being shown in radial section, the diaphragm being shown in its relaxed condition, that is to say before application to a filler neck;

FIG. 2 is an underneath plan except that a central portion is broken away and shows a modification de scribed below; and,

FIG. 3 is an axial section to a reduced scale, through the cap assembly when applied to a filler neckof a petrol tank.

The filler cap assembly comprises a main body 10 made up of a dished central wall 12, an axially extending peripheral wall 14 having gripping serrations, and two diametrically opposed lugs 16 projecting inwards. The only other component of the assembly is a sealing diaphragm 20.

The diaphragm 20 is a one-piece plastics moulding which is continuous, meaning that it has no substantial openings or apertures over its surface, although there can be,'for example, a small vent or a fastening aperture, described in more detail below in relation to modifications.

The diaphragm has the same form, viewed in radial section, around its entire periphery. This is seen best in the lower half of FIG. 1. There is a frusto-conical first wall 22 which is divergent in the direction towards the cap. It joins to an annular second wall 24 which lies at the outer edge of the diaphragm. The first wall 22 joins through a smooth crest to a thir wall 26 which is also frusto-conical but is convergent towards the cap body, and is twice as long. The third wall joins to a fourth wall 28 which is generally planar and abuts the undersurface of the dished central wall 12 of the cap body 10.

In radially outward sequence, the fourth wall 28 increases in thickness, the third wall 26 diminishes, the crest and the first wall 22 are uniform, being the thinnest part of the diaphragm, then the second wall increases and terminates in a rounded bulge. The first wall 22 has substantially the same inclination to the axis as the third wall 26, but twice the axial extent, hence the second wall 24 lies spaced a considerable distance from the wall 12 of the cap.

When the cap assembly is applied to a filler neck, the second wall 24 first abuts the rim of the neck. Increased manual pressure on the body of the cap when the lugs 16 coincide with openings, not shown, in the outwardly turned rim 17 on the neck, presses the second wall 24 towards the wall 12. The wall 24 remains planar and does not stretch, the increasing pressure therefore causes the third wall 26 to bend radially outwards in the vicinity of the crest, and the first wall 22 simultaneously to turn anticlockwise, as viewed in the lower half of FIG. 2, until the portion of the wall 22 adjacent to the second wall abuts the interior surface of the neck as shown in FIG. 3. The body of the cap is then turned about its axis for the lugs 16 to engage under the rim 17. After a short turning action the lugs 16 engage a portion of the rim, not shown, which slopes slightly upwards, but terminates at an axial abutment surface. The spring action of the diaphragm pressing downwards on the rim 17 thus urges the cap body upwards, and so urges the cap body to turn for the lugs 16 to abut the abutment surfaces. The cap rests with stability at this fastened condition, in which the diaphragm maintains its downward sealing pressure on the rim 17, and maintains the deformed cylindrical portion of the wall 22 pressed tightly against the interior surface of the neck, as shown in FIG. 3.

In this preferred diaphragm, there is provided a vent through which air can pass into and out of the petrol tank during use, but through which petrol cannot leak at more than the specified rate when the car is inverted in the event of an accident. The vent is in the form of a labyrinthine groove 30 formed in that face of the fourth portion 28 of the diaphragm which abuts the undersurface of the dished portion 12 of the body of the cap. Its form is seen in detail in FIG. 2. A small passage 32 seen in FIG. 1 opens between the interior of the tank, in use, and the groove. Air can pass readily freely ggound the rim of the diaphragm to reach the groove A major advantage of the diaphragm shown is that it can operate effectively with a range of sizes and shapes of filler necks, the range being well beyond the limits of manufacturing tolerance. Moreover, it can maintain a good continuous seal even on a neck which is not circular because the action of the first and second walls gives good radial pressure against the filler neck, and can maintain the radial pressure against non-circular necks. That radial pressure is released by removal of the cap assembly from the filler neck.

It is to be noted that the pressure is also maintained between the second wall 24 and the rim 17, without any portion of the diaphragm passing around the radially outer portions of the rim. Such a gripping action is not permissible on petrol tanks unlike bottles for which it is known to provide resealable closures of plastic which grip the outer portion of the bottle rim to achieve their seal. The seal between the two walls of the diaphragm and the corresponding two surfaces of the neck in the present case is maintained completely by the interlocking of the cap body and the filler neck through the lugs 16.

However, the present invention is not limited in any way to the lugs or any other fastening means. It is clear that the diaphragm which is the subject of the present invention can be incorporated into filler cap assemblies having alternative fastening means to that shown. Slight obvious modifications which might be necessary to the diaphragm, such as reshaping its outline, lie within the scope of the present invention.

In the cap assembly described above the diaphragm is retained within the cap body by the lugs 16. If the diaphragm is incorporated into a cap assembly which has radially outwardly projecting lugs, or in cap bodies which have no radially inward projections at all, the diaphragm could have a central aperture through which a lug formed on the interior surface of the domed portion 12 could pass, and be swaged over to hold the diaphragm in place. Alternative obvious modifications are obviously possible, and are within the scope of this invention.

Almost any plastics material is suitable for making the diaphragm, provided it is sufficiently flexible and has a good memory. Preferred materials are polythene and polypropylene. The cap body can be of glass-filled polypropylene, metal, or any other suitable material which is not affected by petrol and is sufficiently rigid.

We claim:

1. A two piece petrol cap assembly for application to the filler neck of an automobile petrol tank, said cap assembly comprising a one-piece overcap body and a one-piece plastic diaphragm, said cap body and diaphragm having mutually cooperating means to permit them to be relatively rotatably coupled together as a unit, said cap body having means adapted to mutually cooperate with securing means on the neck of said petrol tank, said diaphragm being substantially continuous and presenting an annular wall which extends radially outwardly and includes the outer margin of said diaphragm, said diaphragm in its relaxed condition when coupled with said overcap being spaced axially from said cap body in the vicinity of said annular wall, said diaphragm having another wall radially inwardly of said annular wall which extends a substantial distance angularly inwardly relative to the axis of said cap body and capable of being moved radially outward to form a continuous seal against the interior surface of said neck upon mounting of said cap and diaphragm unit on the neck of the petrol tank as said cap is progressively pressed onto the rim of said filler neck of said tank, the seal between the two wall of the diaphragm and the inner surface and rim of the neck being continuously maintained by said securing means operative between said cap head and filler neck, said diaphragm further having means abutting the cap body, said means having a fine labyrinthine passage over its outer surface and a small passage opening through the diaphragm to a radially inner portion of the passage. 

1. A two piece petrol cap assembly for application to the filler neck of an automobile petrol tank, said cap assembly comprising a one-piece overcap body and a one-piece plastic diaphragm, said cap body and diaphragm having mutually cooperating means to permit them to be relatively rotatably coupled together as a unit, said cap body having means adapted to mutually cooperate with securing means on the neck of said petrol tank, said diaphragm being substantially continuous and presenting an annular wall which extends radially outwardly and includes the outer margin of said diaphragm, said diaphragm in its relaxed condition when coupled with said overcap being spaced axially from said cap body in the vicinity of said annular wall, said diaphragm having another wall radially inwardly of said annular wall which extends a substantial distance angularly inwardly relative to the axis of said cap body and capable of being moved radially outward to form a continuous seal against the interior surface of said neck upon mounting of said cap and diaphragm unit on the neck of the petrol tank as said cap is progressively pressed onto the rim of said filler neck of said tank, the seal between the two wall of the diaphragm and the inner surface and rim of the neck being continuously maintained by said securing means operative between said cap head and filler neck, said diaphragm further having means abutting the cap body, said means having a fine labyrinthine passage over its outer surface and a small passage opening through the diaphragm to a radially inner portion of the passage. 